fix(trace): avoid allocation while swapping profiles - #15720
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Capture sampled heap state in references allocated before taking the profile mutex, then construct the snapshot tuple after releasing it. This prevents an allocation callback from recursively acquiring the sample mutex. Signed-off-by: Rudi Grinberg <me@rgrinberg.com>
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Alloc.swapcurrently constructs its result tuple while holding the allocation profiler's sample mutex. At sufficiently high sampling rates, that allocation can invoke a Memprof callback which attempts to acquire the same mutex, terminating Dune withMutex.lock: Resource deadlock avoided.Capture the sampled heap fields in references allocated before taking the mutex, and construct the returned tuple only after releasing it. This keeps the critical section allocation-free without changing the snapshot contents.